High molecular weight copolyesters prepared from dicarboxylic acids or their esters and mixtures of long chain glycols and low molecular weight diols are thermoplastic and exhibit elastomeric properties. These materials have good low temperature properties, high abrasion resistance and extremely good hydrolytic stability and resistance to many organic fluids in addition to useful physical properties at ambient and elevated temperatures. Because of their thermoplastic nature, these copolyesters can be processed by substantially any procedure used for thermoplastics in general. Their good thermal stability and low melt viscosities provide outstanding processing safety.
It has been found, however, that the preparation of composite structures from these copolyesters wherein it is desirable to adhere or bond the copolyester to substrates such as fiber forming condensation polymers and regenerated cellulose is complicated by the fact that the copolyesters have limited affinity for materials such as polyesters e.g. poly(ethyleneterephthalate) and polyamides e.g. poly(hexamethylene adipamide). In order to take advantage of the properties and processability of this class of copolyesters in composite structures, convenient and economical means for adhering the copolyesters to the above-described substrates is needed.